Method and device for inserting needles

ABSTRACT

The invention relates to a device for inserting needles, including a body defined by a proximal end and a distal end, a mounting movably mounted inside the body, at least one needle secured to the mounting, a drive means suitable for driving the mounting towards said distal end, said mounting comprising a distal surface onto which the needle projects, said distal end comprising a contact area intended for contacting the tissue, the mounting being configured so as to reach a position, after activating the driving means, in which the distal surface thereof, relative to said proximal end, is more distant than said contact area, wherein the device is further configured so as to enable a gradual passive return movement of the mounting once said position has been reached.

FIELD OF THE INVENTION

The present invention relates to the insertion of needles, particularlymicroneedles. This may be used for intradermal or subcutaneous injectionof solutions.

PRIOR ART

Devices for the insertion of microneedles are disclosed in the followingdocuments: U.S. Pat. No. 6,743,211, U.S. Pat. No. 4,886,499, U.S. Pat.No. 7,083,592 and US 20100030148.

GENERAL DESCRIPTION OF THE INVENTION

The present invention constitutes an improvement over the methods anddevices of the prior art. It is characterized in particular in that thetissue can be struck by one or more microneedles at relatively highspeeds, typically of the order of 7 m/s, while at the same time allowingthe tissue to deaden the impact over a certain distance, this having theeffect of improving the perforation of the tissue and of returning thistissue to a stable state of equilibrium, thereby minimizing stresses.

In the context of the present invention, the microneedles are free ofany physical pressing at the time of injection. The pressure generatedby these needles cannot therefore oppose the formation of papules whichare brought about by the intradermal injection. It is also possible tofollow the growth of the profile of the papule so as to ensurecontinuity of injection without leaks.

Expressed in a different way, the present invention is characterized bya partial or complete disappearance of the pressure exerted by theneedles—or more generally by the needle carrier—on the tissue once theneedles have penetrated this tissue, the consequence of this being thatthe tissue is made to return as closely as possible to its state ofequilibrium without residual stress.

A subject of the present invention is, therefore, a device for insertingneedles comprising a body defined by a proximal end and a distal end, acarrier mounted with the ability to move inside the body, at least oneneedle secured to the carrier, drive means designed to drive the carriertoward said distal end and an activation mechanism for activating thedrive means, said carrier comprising a distal face from which the needleprojects, said distal end comprising a contact zone intended to comeinto contact with the tissue, the carrier being configured so that itreaches a position, following activation of the drive means, in whichits distal face, with respect to said proximal end, is further away thansaid contact zone; the device being further configured to allow thecarrier to recoil in a passive manner once said position has beenreached.

In one possible embodiment, the device may have a body of elongate shapein which a piston is slidably mounted, the needle projecting from saidpiston.In one possible embodiment, the drive means may be a thruster housing aspring and driving the piston by contact.In one possible embodiment, the needles of the device are microneedles.Microneedles means needles the dimensions of which are designed totarget the intradermal territory. This zone has a thickness that canvary according to the patient and according to the position on the bodyof one and the same patient. It is of the order of a few hundredmicrons. However, the microneedle may be slightly longer than themaximum thickness of this zone in order to take account of the fact thatthe penetration of microneedles into the tissue could be only partial.

In the context of the present invention, the pressure from the start tothe end of papule formation is minimal. Once insertion has beenachieved, the needle, by way of force exerted on the tissue and on thepapule, exerts at most its own weight, that of the carrier and anyfriction forces that might exist. The physical pressing for fixing thetissue and holding the device in place occurs far from the injectionsite and any pressing on the device is not transmitted directly to theneedle because the piston can slide.

For preference, the device according to the invention is dimensioned insuch a way that when applied to the tissue, the needle or needles comeinto contact with the tissue before the piston becomes restrained by astop. The length over which the piston is thus deadened by the tissuecan range between a fraction of the length of the needle and 10 mm.

If the thruster is restrained by a stop before the needle or needlescome into contact with the tissue then the needle or needles, ifappropriate connected to an injection line used to deliver a substance,may become detached from the thruster and continue their journeyindependently of this thruster and thus penetrate the tissue.

Injection may be triggered automatically or manually once the needle orneedles are inserted in the tissue, but it will preferably begin oncethe tissue has returned to its state of equilibrium. Intradermalinjection may, in some instances, lead to the formation of a papulewhich corresponds to the deformation of the tissue following the storageof the solution injected into the tissue, notably during an injection ofthe bolus type.

It should be noted that the creation and maintaining of a papule aredesirable in order to ensure optimal injection. This is why the presentinvention allows such a papule to form and to remain in place for longenough for the injected substance to diffuse correctly.

A mechanism may make it possible to maintain a maintaining force up tothe moment of injection, at which point this force will be canceled.

It should also be noted that, with the present invention, the pressingof the device on the tissue is independent of the pressing of the needleor the needles on the tissue.

It should also be noted that the pressing system of the device also hasthe task of setting the distance separating the needle or needles fromthe surface of the tissue before said device is activated.

The invention also relates to a method of insertion and of injectionusing one or more needles, notably microneedles, and notably into thedermis, in which the needle to which a translational movement has beenimparted can decelerate in the tissue because of the elasticity of thetissue over a certain length, while at the same time in fine allowingpartial or total spring back to the state of equilibrium (or close tothat state) under the simple effect of the elasticity of the tissue. Theneedle can therefore move freely over a certain distance, whichcomprises the surface of the tissue. The needle can move into the tissueand push the latter beyond its initial height at equilibrium. Similarly,once the needle is partially inserted in the tissue, a hard, partial orprogressive limitation may prevent it from returning backward (opposingforce) beyond or not as far as the natural (initial) equilibrium height.The needle will position itself at the point of equilibrium between theelastic force of the tissue and this potential opposing force. Forpreference, post-insertion equilibrium needs to be as close as possibleto the natural equilibrium of the tissue, or even with a slight opposingforce to prevent the withdrawal of the needle from the tissue. Forpreference, the opposing force needs to prevent the needle from comingback out of the tissue through an inertia effect when the tissue regainsits equilibrium, but this opposing force needs not to prevent injection.In particular, this opposing force needs not to create any pressurewithin the tissue that might prevent or limit correct diffusion of thesubstance that is to be infused.

At the time of the injection, the needle remains secured to the papule,moving with it as it grows, offering a minimum of resistance. A slightopposing force, in addition to the weight if the position is a verticalone, may be present, in order to keep the assembly in place.

For preference, the thruster is set in motion by the release ofpotential energy, in this instance a spring. This energy may adoptvarying forms, plastic spring, leaf spring, gas cartridge, compressedair, electro-magnetic force, generation of gas through chemical reactionbetween at least two compounds. The piston may be set in motion directlywithout the aid of a thruster, using only the source of energy. Theenergy source may be the user himself. By pressing with sufficientforce, he will, via a mechanism internal to the device, generate thespeed needed to cause the needle or needles to penetrate the tissue.

The device also comprises a safety mechanism, allowing the activationmeans to be locked in order to avoid unintentional triggering. In theinstance discussed here, this is a second safety button that has to beactivated before pressing on the insertion trigger. The safety mechanismmay adopt various forms, and the pressing of the ring or of the deviceagainst the tissue may also unlock the activation trigger.

For preference, the device also comprises a container used to storesubstance for administering. This container may be positioned on thebody of the device, or incorporated directly into the device. Activationof this container, which will cause the substance to be injected intothe tissue, may be either manual or automatic. In the latter instance,activation of the device will, once the needles are in place, lead toactivation of the container. This container may adopt various forms suchas—and this list is not exhaustive—a semirigid reservoir, a flexiblepouch, a syringe, a carpule.

The device may comprise a mechanism which makes the needle difficult toaccess in order to prevent injuries, before or after insertion and afterinjection when the device has been used for this purpose. Thisprotection may notably be obtained by retracting the needle into thebody of the device, or into the carrier itself, or by sliding a coverwhich prevents access to the needle.

Use of the device is not restricted to a vertical position.

For preference, the device is oriented to allow the needles to penetratethe tissue perpendicularly, although in certain embodiments, this anglemay be modified.

DETAILED DESCRIPTION OF THE INVENTION

The invention will be described in greater detail hereinbelow throughsome nonlimiting embodiments illustrated by figures.

FIG. 1: Depiction of one embodiment of a device according to theinvention. A needle (4) is secured to a piston (3) via a connector (7).The thruster (1) is released behind the piston (3), and the empty space(1 a) for sliding can be seen between the two of them.

FIG. 2: In this preferred configuration, the device is placed on thetissue (6 a) via contact with an outer ring (8). The device has beenarmed and triggered. The thruster (1) has pushed the piston (3) and hasjust come into abutment (5 a) against a stop (cf. stem in the thruster).The piston (3) will continue its travel under the effect of inertia. Forthis configuration, the instant at which the piston (3) will detach fromthe thruster (1) corresponds on average to the instant at which theneedle (4) begins to penetrate the tissue.

FIG. 3: Same device as that of FIG. 2. The piston (3) has continued itstravel under the effect of inertia, the needle (4) penetrates andcompresses the tissue (6) to an increasing extent as the elastic returnforce of the tissue (6) increases with deformation, the piston (3)decelerates until the inertia force drops below the elastic returnforce, at which point the needle (4) insertion is at a maximum. Themovement then reverses with the tissue returning to its “natural”initial state of equilibrium (cf. 6 a in FIG. 2).

FIG. 4: According to another embodiment, the sizing is such that thepiston (3) encounters an abrupt stop (3 a) on the body of the devicebefore the inertia force is equalized with the elastic return force ofthe tissue (6). It is also possible to conceive of partial stop orprogressive type of return force.

FIGS. 5 and 6: In another variant of the invention, the sizing is suchthat the piston (3) becomes detached from the thruster when the needlehas not yet come into contact with the tissue.

FIG. 7: The elastic force returns the piston (3) to its initialposition, the needles (4) remaining well inserted into the tissue (6 a);the thruster (1) then offers a return force attenuating any oscillatoryeffect and preventing the piston (3) from rebounding under the effect ofinertia and causing the needle (4) to come out of the tissue (6).Equilibrium is reached with the deformations imposed on the tissue (6)relaxed but with the needle still correctly inserted. A small residualforce from the tissue and a small opposing force from the thruster (1)may be enough to keep the needle (4) in place.

FIG. 8: The injection can begin, preferably at equilibrium, the papule(6 b) which is forming drives the piston (3) which can slide withoutputting up a great deal of resistance and allowing the needle (4) toremain correctly inserted in the papule (6 b), guiding the movement. Inthis instance, the spring (2) of the thruster is at the end ofcompression and puts up only a weak opposing force opposing theformation of the papule (6 b), in addition to the light weight of theassembly comprising piston (3), connector (7), needle (4) and tube.

FIG. 9: In this variant, the opposing force of the thruster (1) is notapplied, the height adopted by the piston (3) as a result of theformation of the papule (6 b) being smaller than the free distancebetween the thruster (1) against the stop (5 a) and the piston (3).

FIG. 10: In this other variant, at equilibrium, the thruster (1) ismoved away (e.g. recompressed, spring relaxed upward, thruster stageraised) to leave the piston (3) empty space into which to rise as thepapule (6 b) forms. This is a return to the configuration of theinitiator for injection, but ensuring the opposing force to the elasticforce at the time of insertion.

FIG. 11: Depiction of an embodiment of the device according to theinvention. A needle (9) is secured to a piston (11). A leaf spring (12)is placed under spring-load between the piston (11) and the housing (10a).

FIGS. 12-13: In this configuration, the device is placed on the tissue.The device has been triggered. The spring (12) relaxes and pushes thepiston (11) which comes into abutment with the tissue (14). The piston(11) will continue its travel under the effect of inertia. In thisconfiguration, the moment at which the leaf spring breaks contact withthe housing (10 a) corresponds on average to the moment at which theneedle (9) begins to penetrate the tissue (14).

FIG. 14: The injection can begin, preferably at equilibrium, the papule(14 a) that is forming pushes the piston (11) which can slide withoutputting up any great resistance to this sliding and allowing the needle(9) to remain correctly inserted in the papule (14 a), guiding themovement. Here the spring (12) is decompressed and offers no opposingforce that opposes the formation of the papule (14 a).

FIG. 15: Depiction of an embodiment of a device according to theinvention. A needle (15) is secured to a piston (17). A mechanical“rod-crank” system (21, 22) allows the rotational movement brought aboutby the spring (18) to be converted into a translational movement of thepiston (17). The piston (17) can slide in the guideways of the housing(16 a).

FIG. 16: In this configuration, the device is placed on the tissue. Thedevice has been triggered. The spring (18) relaxes and activates the“rod-crank” system (21, 22) which pushes on the piston (17) that hasjust come into abutment against the tissue (16). The piston (11) willcontinue its travel under the effect of inertia.

For this configuration, the moment at which the spring is relaxedcorresponds on average to the moment at which the needle (15) begins topenetrate the tissue (20).

For another configuration, the spring is able to maintain a certainforce pressing the piston (17) against the tissue (20), pressing thebutton allows the force applied by the piton (17) to the tissue (20) tobe released.

FIG. 17: Injection can begin, preferably at equilibrium, the papule (20a) that is forming pushes the piston (17) which can slide withoutoffering a great deal of resistance and allowing the needle (15) toremain correctly inserted in the papule (20 a), guiding the movement.Here, the spring (18) is decompressed and offers no opposing forceopposing the formation of the papule (20 a), the “rod-crank” system(21,22) allows the piston (17) to return as the papule (20 a) forms.

1. A device for inserting needles comprising a body defined by aproximal end and a distal end, a carrier mounted with the ability tomove inside the body, at least one needle secured to the carrier, drivemeans designed to drive the carrier toward said distal end, said carriercomprising a distal face from which the needle projects, said distal endcomprising a contact zone intended to come into contact with the tissue,the carrier being configured so that it reaches a position, followingactivation of the drive means, in which its distal face, with respect tosaid proximal end, is further away than said contact zone; the devicebeing further configured to allow the carrier to recoil in a passivemanner once said position has been reached.
 2. The device as claimed inclaim 1, in which the carrier is formed of a piston and of a connector,said distal face being positioned on the connector.
 3. The device asclaimed in claim 1, in which the body comprises a first stop elementarranged in such a way as to restrain the carrier when it is driventoward said distal end.
 4. The device as claimed in claim 1, in whichthe body comprises a second stop element positioned in such a way as torestrain the drive means when they are driven toward said distal end. 5.The device as claimed in claim 2, in which the drive means are inmechanical contact with the piston when the piston moves toward saiddistal end and when an empty space is formed during the recoil phase ofthe piston.
 6. The device as claimed in claim 1, in which the drivemeans comprise a spring.
 7. The device as claimed in claim 2, in whichseveral needles are secured to the piston via the connector.
 8. Thedevice as claimed in claim 2, comprising means for restraining thepiston which means are positioned in such a way as to allow the pistonto recoil over a predefined distance.
 9. The device as claimed in claim1, in which a container able to contain a substance that is to bedelivered through the needle forms an integral part of the device, ispositioned on the body of the device or is connected directly to amoving part.
 10. The device as claimed in claim 1, comprising anactivation mechanism for activating the drive means.
 11. The device asclaimed in claim 1, comprising a safety mechanism which locks the drivemeans or the activation mechanism that activates the drive means. 12.The device as claimed in claim 1, comprising a mechanism that makesaccess to the needle difficult so as to prevent injury, before or afteruse.
 13. The device as claimed in claim 12, in which the needle isretracted into the body of the device.
 14. The device as claimed inclaim 12, in which a retractable cover prevents access to the needle.15. The use of an assembly for inserting needles and for injectingsolutions, comprising the following steps: a) insertion of at least oneneedle into or through the tissue, b) first passive retraction of theneedle as a result of a return of the tissue to the state ofequilibrium, c) injection of at least one solution through the needle.16. The use as claimed in claim 15, in which said steps are performed insuccession.
 17. The use as claimed in claim 15, in which steps b) and c)are performed simultaneously.
 18. The use as claimed in claim 15,further comprising the following step: d) second passive retraction ofthe needle resulting from the formation of a papule following step c).